Predictive value of microalbuminuria in medical ICU patients: results of a pilot study

To evaluate the predictive value of microalbuminuria in the development of acute respiratory failure (ARF) and multiple organ failure (MOF) in ICU patients.

Prospective, observational study.

A 31-bed, mixed medicosurgical ICU in a university hospital.

All adult medical patients admitted to the ICU over a 2-month period, except those receiving nephrotoxic drugs, or those with urologic trauma resulting in frank hematuria or urinary infection, or with existing chronic renal disease (serum creatinine level > or 2.0 mg/dL).

None.

Urinary samples for microalbumin measurement were collected at hospital admission and at 8, 24, 48, 72, 96, and 120 h after hospital admission. The severity of illness was assessed by the APACHE (acute physiology and chronic health evaluation) II score calculated on the first ICU day, and the degree of organ dysfunction was assessed using the sequential organ failure assessment (SOFA) score. Acute respiratory failure (ARF) was defined as a SOFA respiratory score > or = 3. Patients were separated into two groups according to the trend in microalbuminuria levels over the first 48 h: patients in group 1 had increasing microalbuminuria levels, and patients in group 2 had decreasing microalbuminuria levels. Group 1 included 14 patients in whom microalbuminuria levels increased from 5.2 +/- 2.0 to 19.0 +/- 3.0 mg/dL. Group 2 included 26 patients in whom microalbuminuria levels decreased from 16.4 +/- 4.0 to 7.8 +/- 3.0 mg/dL. The hospital mortality rate was 43% in group 1 and 15% in group 2 (p < 0.05). The APACHE II score and the SOFA score were higher in group 1 than in group 2. The negative predictive value of increasing microalbuminuria was 100% for the development of ARF and 96% for MOF; the positive predictive value of increasing microalbuminuria was 57% for the development of ARF and 50% for MOF.

Accurate identification of patients destined for ARF and MOF development may enable therapeutic strategies to be applied to limit the disease process. Trend analysis of urinary albumin excretion over the first 48 h of an ICU admission may provide a useful means of identifying such patients. Additional studies need to be performed in larger, mixed patient populations to confirm these findings.